After a relay node (Relay Node, RN) is introduced into a long term evolution (Long Term Evolution, LTE) system, a user equipment (User Equipment, UE) may access a base station through the RN, where the base station is an evolved NodeB (evolved Node B, eNB). In this way, a radio interface (radio interface) from the UE to the eNB changes from a single-hop radio interface to a multi-hop radio interface.
In the existing LTE system, the quality of service (Quality of Service, QoS) of the radio interface from the UE to the eNB is generally maintained by scheduling. The scheduling mainly includes the uplink scheduling and downlink scheduling performed by the eNB. Generally, the following parameters are considered for the scheduling: channel quality, QoS parameter information, sleep cycle and measurement gap (GAP) of the UE, state information of a service, and system parameters (for example, system bandwidth). In a bearer setup process, a policy and charging rules function (PCRF) first decides QoS parameters of an evolved packet system (Evolved Packet System, EPS) bearer by using a policy and charging control (PCC) judgment mechanism; a device on the core network sends the QoS parameters of the EPS bearer to the eNB through a bearer setup request message; after receiving the bearer setup request message, the eNB maps the QoS parameters of the EPS bearer to QoS parameters of a radio bear (Radio Bear, RB for short) to perform corresponding RB configuration and use the QoS parameters as the scheduling parameters of the radio interface. When the UE accesses the eNB through a single hop, the eNB only needs to schedule the single-hop link according to the QoS parameters of the RB and in combination with other scheduling parameters to maintain the QoS parameters of the bearer.
After the RN is introduced into the LTE system, the radio interface changes from a single-hop radio interface to a multi-hop radio interface. Different from the scheduling of the link from the UE to the eNB in a single-hop scenario, the scheduling in a multi-hop scenario is divided into centralized scheduling and distributed scheduling. Assuming that a transmission path from the UE to the eNB is UE<—>RN1<—>RN2<—>eNB, that is, the path from the UE to the eNB passes through two RNs and the radio interface is a three-hop radio interface, where “<—>” is a double arrow, indicating a link between a left node of the double arrow and a right node of the double arrow. Through the link, the two nodes can exchange signaling and data information with each other. In a distributed scheduling mode, the eNB is responsible for scheduling the RN2<—>eNB link, the RN2 is responsible for scheduling the RN1<—>RN2 link, and the RN1 is responsible for scheduling the UE<—>RN1 link. In the distributed scheduling mode, parameters considered in the scheduling of the link from the UE to the eNB in the single-hop scenario are not applicable, for example, a delay parameter in the QoS parameters. A considerable delay may increase in the service data in each hop relay process. In addition, the impact of the delay on a time division duplex (TDD) system and a frequency division duplex (FDD) system may vary. Therefore, according to QoS parameters that need to be maintained in the UE<—>eNB transmission path, the existing eNB determines QoS parameters that need to be maintained by the links undertaken by each RN, and delivers the determined QoS parameters to each RN, so that each RN can schedule the links undertaken by the each RN. Therefore, the QoS maintenance mechanism cannot meet the QoS maintenance requirements in the multi-hop scenario.